Method of discovering operator-provided network-services using IMS

ABSTRACT

A method, a session managing node and an arrangement for providing a network-service address of at least one network-service of an IMS network ( 401 ) of a first operator to a third party service provider ( 403 ), wherein the third party service provider has no business agreement with the first operator. A first application ( 404 ) of a mobile station is communicating with a second application ( 405 ) via a first network ( 406 ), resulting in the set-up of an IMS-session, between the mobile station and the third party service provider. A network-service address of at least one network-service, provided by the IMS network of the first operator, is inserted into a SIP message of the IMS-session in a session managing node ( 600 ) of the IMS network of the first operator and delivered to the third party service provider, where it is forwarded to the second application. If required, the second application may access the one or more network-services via the first network, using the retrieved network-address.

TECHNICAL FIELD

The present invention relates generally to a method and arrangement forproviding a third party service provider access to network-servicesoffered by an IMS network of an operator with which the third partyservice provider has no prior business relation.

BACKGROUND

IMS (IP Multimedia Subsystem) is a set of standards providing thesignalling, delivery, authentication and billing functions necessary forreal-time, packet-based calls and services across virtually anyunderlying network technology. In other words, IMS is a platform adaptedfor an efficient and rapid implementation of next-generation IP servicesin both fixed and mobile networks which will accelerate the convergenceof fixed and wireless networks.

A common description of a driving vision behind IMS is the focus ongiving subscribers consistent, converged services in daily lifecommunication, involving the concept of “one handset device, one addressbook, one email address, and one bill” from all service sessions acrossall networks, comprising traditional telephony, as well as Internetcommunication over all wire-line and wireless transports.

Normally, IMS subscribers have a plurality of IMS operators to choosefrom, each having different services and prices to offer. Typically anIMS subscriber has a business agreement with one of the IMS operatorsoperating on the market. From the IMS subscribers point of view,however, it is desirable to have access to a wider range of service thanwhat can be offered by one chosen IMS operator. In order to be able tosatisfy its subscribers, IMS operators often have mutual businessagreements with each other, whereby one IMS operator can offer or makeuse of another IMS operators services.

FIG. 1 illustrates one way of delivering services from a third partyservice provider 103 to a user of a mobile station 100 over IMS,according to the prior art. The user of mobile station 100 is asubscriber of a first IMS operator managing an. IMS network 101. Thefirst IMS operator, however, do not have any direct business relationwith the third party service provider 103, and, thus, it is not obviousthat the mobile station 100 can access services from the third partyservice provider 103 via IMS network 101.

The third party service provider 103 have a business relation with asecond operator, managing a second IMS network 102. The user of themobile station 100, activates an application 104, which recognises arequirement for a service, which can not be accessed from IMS network101, but which is accessible from the third party service provider 103.A necessary condition for the first operator to be able to offer thisservice to the user of mobile station 100 is that the first IMS operatorhas an interconnection agreement with the second IMS operator. In such asituation, the mobile station 100 may set-up an IMS session with thethird party service provider 103, by first connecting with the firstoperators IMS network 101 in a step 1:1. The first operator of IMSnetwork 101, having an interconnection agreement with the secondoperator of IMS network 102, sets up an interconnection between the twoIMS networks in a second step 1:2, and the second operator completes theIMS-session by connecting to the third party service provider 103 in athird step 1:3. After having completed the signalling (not shown),verifying a successful IMS session set-up from the third party serviceprovider 103, the application 104 of the mobile station 100 may accessservices, provided from an application 105 of the third party serviceprovider 103, via the IMS session in a final step 1:4.

In another scenario, a third party service provider wanting to enhanceits service offering may have a requirement to be able to access certainservices from one or more network operators, other than its ownoperator. In order to do so there has to be a business agreement betweenthe two service providers. Such network-services may include, e.g. userstatistics, location information or control of communication quality(QoS), and may be provided via standardised or published interfaces,such as e.g. parlay or different types of web services.

A prior art scenario illustrating this type of situation will now bedescribed with reference to FIG. 2, wherein a third party serviceprovider 203, providing services to a user of a mobile station 200, viaa first network 206 wants to enhance its services by using an additionalnetwork-service provided from an IMS network 201 of a first operator. Auser of mobile station 200, has initiated an application 204, whichrequires a service, accessible from the third party service provider203. Initially, the application 204 of the mobile station 200establishes a connection with an application 205 of the third partyservice provider 103 in a first step 2:1, via the first network 206. Ina next step 2:2, the application 105, recognising a requirement for anetwork-service which can not be provided from the third party serviceprovider, but from the IMS network 201 of the first operator. Theapplication 205, therefore, establishes a connection with IMS network201, after which the required network-service can be accessed and usedby the application 205. In order for the third party service provider tobe able to access the required service from the IMS network 201 of thefirst operator, however, the third service provider 203 has to have abusiness relation with the first operator.

As mentioned in both prior art scenarios presented above, it isnecessary to have established a business relation between two parties ifthey are to be able to use each others services, and thereby be able toprovide an enhanced range of services to its subscribers.

FIG. 3 illustrates how different business agreements can be set upbetween a first operator, managing a first IMS network 301, a secondoperator, managing a second IMS network 302, a user of a mobile station300, and a third party service provider 303, i.e. the participantspresented in FIG. 1.

In FIG. 3, the user of mobile station 300 is a subscriber of theoperator of IMS network 301, and, thus, a business agreement 304,defined as a subscription, is established between these two parties.

In the figure, the first operator of IMS network 301 also has a businessrelation 305, defined as an interconnection agreement with the secondoperator of IMS network 302. As an alternative to a directinterconnection agreement between the first IMS network 301 and thesecond IMS network 302, a business relation may be set up between thetwo IMS networks via a transit network (not shown), which may have aninterconnection agreement with both IMS networks.

The third party service provider 303, may have another business relation306 with the second IMS operator to use the second IMS network 302. Inaddition, the figure illustrates that the user of the mobile station 300also may have a business relation 307 set-up directly with the thirdparty service provider 303, via a separate network 308.

Failure for parties to get access to network-services offered by certainoperators may obstruct an operator from being able to offer competitiveservices to its subscribers, and may also become an obstacle for theoperator in the development of new services. Creation of businessrelations with all major operators will, however, require great effortsfrom the operators and third party service providers involved.

SUMMARY

The object of the present invention is to address at least some of theproblems outlined above. In particular, it is an object to provide asolution which enables a user connected to a third party serviceprovider to gain access to services, including one or more supplementaryservices available from an operator that has no prior business relationwith the third party service provider.

According to different aspects, a method and an arrangement are definedfor providing a network-service address of network-services provided byan IMS network of an operator with which a third party service providerhas no business relation. By adapting a session managing node toautomatically insert the network-service address of the respective oneor more network-services into a SIP message of an IMS-session, set-upbetween a mobile station and a third part service provider, indirectlyrequiring the one or more network-services when accessing a service fromthe third party service provider, network-services will be easilyaccessible to the third party service provider and to a user of a mobilestation without requiring any prior business relation between the thirdparty service provider and the respective operator providing the one ormore network-services.

Such an automatic address delivery procedure may be restrictive by usingone or more black lists, restricting which parties that are entitled toget access to network-services provided by the respective operator.

According to further aspects, a method of a third party service providerfor retrieving a network-service address of at least onenetwork-service, offered by an IMS network (401) of a first IMSoperator, wherein the third party service provider has no businessagreement with the first IMS operator, is defined. An application of thethird party service is activated from a mobile station via a firstnetwork. In a next step an IMS-session is established between the thirdparty service provider and the mobile station via the first IMS network.Finally, the network-service address of one or more network-services isretrieved at the application of the third party service provider,wherein the network-service address has been inserted into a mobileoriginated SIP message of the IMS-session by a session managing node(600) of the first IMS network.

According to one aspect, the first network is the Internet.

According to another aspect, the IMS-session is established via thefirst IMS network, and a second IMS network of a second operator, withwhich the third party service provider has a business agreement. Thefirst operator may have a business agreement with the second operator.Alternatively, the two IMS networks may be interconnected via a transitnetwork.

According to yet another aspect, the network-service address is insertedinto a new network-services address header of the SIP message.

According to one aspect, one or more network-services are accessed via anetwork service enabler interface, using the inserted network-serviceaddress. The network-service address may be an address to a catalogue ofnetwork-services, or to a specific network-service. Alternatively, thenetwork-service address may be an address to a structure, comprising atleast one network service enabler address. The catalogue or structuremay also comprise an identifier for each network-service, specifyingwhat protocol to use to access a respective network-service.

According to another aspect, also a session identifier may be insertedinto the SIP message.

According to one embodiment, the IMS-session is mobile stationoriginated and the network-service address is inserted into a SIPINVITE.

According to another embodiment, the IMS-session is instead mobilestation terminated and the network-service address is inserted into aSIP RESPONSE.

According to yet another embodiment, the application of the third partyservice provider may determine whether the application requires anetwork-service provided by the IMS network of the first operator, and arequired network-service may be accessed from an application server ofthe IMS network of the first operator via the first network, using theretrieved network-service address.

In another aspect, a method of an IMS network node for providing anetwork-service address of at least one network-service provided by anIMS network of a first operator to a third party service provider,wherein the third party service provider has no business agreement withthe first operator, is provided. According to this aspect, a mobilestation originated SIP message of an IMS-session between the third partyservice provider and a mobile station, accessing a network-service ofthe third party service provider via a first network, is received. Anetwork-service address is inserted into the SIP message, before the SIPmessage is transmitted to the third party service provider. Prior to theinserting steps, a step of interrogating a received SIP message fordetermining whether the terminating and/or the originating part of theIMS-session is registered in a black list (604), may be executed.Depending on the outcome of the interrogation it is determined whether anetwork-service address is to be inserted into the received SIP-messageor not.

According to yet another aspect, a session managing node, is adapted toprovide a network-service address of at least one network-service of anIMS network of a first operator to a third party service provider,wherein the third party service provider has no business agreement withthe first operator. The session managing node is provided with means forreceiving a mobile station originated SIP message of an IMS-session,established between the third party service provider and a mobilestation, accessing a network-service of the third party serviceprovider, via a first network. The session managing node furthercomprises means for inserting a network-service address into the SIPmessage, upon having interrogated the SIP message, and upon havingdetermined that a network-service address is to be inserted into the SIPmessage. The SIP message, comprising a network-service address is thentransmitted to the third party service provider via a transmittingmeans.

In yet another aspect, the inserting means may be adapted to determinethat no network-service address is to be inserted into a SIP message ifthe terminating and/or originating part of the IMS-session is found in ablack list. Furthermore, the network-service address may be providedfrom an address database, which is continuously updated by anapplication server providing network-services. The inserting means maybe adapted to insert a session identifier into the SIP message, and thetransmitting means may be adapted to transmit the SIP message to thethird party service provider via an IMS network (402) of a secondoperator, wherein the first operator has a business agreement with thesecond operator.

In another aspect, an arrangement for a telecommunication systemcomprising a first network, a first IMS network of a first operator,serving a mobile station, and a second IMS network (402) of a secondoperator, wherein the third party service provider has no businessrelation with the IMS network of the first operator, is provided. Thisarrangement comprises means at the third party service provider forestablishing a communication between a first application of the mobilestation and a second application of the third party, via the firstnetwork. The third party service provider further comprises means at thethird party service provider for setting up an IMS session between themobile station and the third party service provider. In addition, thenode comprises means for inserting a network-service address of at leastone network-service, provided by the IMS network of the first operator,at a session managing node of the IMS network of the first operator, andmeans for receiving the network-service address at the third partyservice provider, and for forwarding it to the second application.

According to another aspect, the third party service provider furthercomprises means for determining whether the second application requiresat least one network-service provided from the IMS network of the firstoperator, and means for setting up a connection with an applicationserver of the IMS network of the first operator via the first network,if the second application requires at least one network-service from theIMS network of the first operator for accessing the at least onenetwork-service, using the retrieved network-service address.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described in more detail by means ofexemplary embodiments and with reference to the accompanying drawings,in which:

FIG. 1 is a basic overview of the architecture illustrating anexemplified signalling for allowing a user of a mobile station access toa service provided from a third party service provider, according to theprior art.

FIG. 2 is a basic overview of the architecture illustrating anexemplified signalling for allowing a third party service providerproviding services via a first network, to enhance its service offeringby accessing a supplementary network-service provided from anothernetwork, according to the prior art.

FIG. 3 is a schematic scheme illustrating possible business agreementsbetween the parties earlier mentioned with reference to FIG. 1, as wellas between the parties figuring in the claimed invention.

FIG. 4 is a basic overview illustrating an architecture and signallingfor providing a network-services address to a third party serviceprovider via a mobile originated IMS-session, according to a firstembodiment.

FIG. 5 is a basic overview illustrating an architecture and signallingfor providing a network-services address to a third party serviceprovider via a mobile terminated IMS-session, according to anotherembodiment.

FIG. 6 is a schematic architecture of an IMS network comprising asession managing node adapted to provide a network-services address to athird party service provider.

FIG. 7 is an exemplary structure of the address database, previouslydescribed with reference to FIG. 6.

FIG. 8 is a schematic architecture of a third party service provideroperating in accordance with the described embodiments of the claimedinvention.

DETAILED DESCRIPTION

Briefly described, the present invention provides a solution for a thirdparty service provider to gain access to one or more network-services,provided by an IMS network managed of a first operator, wherein thethird party service provider has no prior business relation with thefirst operator, i.e., no business agreement has been set-up between thetwo parties. This is achieved by way of introducing an addressattachment mechanism, adapted to attach a network-service address,necessary for accessing one or more required network-services, to a SIPmessage delivered between the third party service provider and the IMSnetwork via a SIP session.

According to a first embodiment, described with reference to FIG. 4, auser of a mobile station 400 is a subscriber of an IMS network 401, of afirst operator. Throughout this document, this network will be definedas IMS network A. The user of the mobile station 400 may wish to use aservice provided from a third party service provider 403, which isconnected with, and has a business relation with an IMS network 402 of asecond operator. This IMS network will be defined as IMS network Bthroughout this document.

Via a first application 404, already stored in, or downloaded to themobile station 400, the user of the mobile station 400 establishes acommunication with a second application 405 of the third party serviceprovider 403, via a first network 406, such as, e.g. the Internet, in afirst step 4:1. This first step may be decided upon automatically by thefirst application 404, or in response to an interaction made by theuser.

To enable the third party service provider 403 to provide an enhancedservice program to the user of mobile station 400, it may require accessto one or more network-services, such as, e.g., user statistics,location information or information, related to the quality of service(QoS), provided from IMS network A 401. In this example, an IMSinterconnection agreement has already been established between IMSnetwork A 401 and IMS network B 402, prior to the present interaction.Alternatively, an interconnection agreement has already been establishedbetween IMS network A 401 and IMS network B 402 via a transit network(not shown), as mentioned previously.

No a-priori interconnection agreement has, however, been establishedbetween IMS network A 401, serving the user of mobile station 400, andthe third party service provider 403, served by IMS network B 402. Atthis stage, IMS in itself is obviously not suited to carry allnetwork-services desired by the third party service provider 403 andprovided by IMS network A 401. Instead, the third party service provider403 may access the required one or more network-services via the firstnetwork 406, via an existing network-service enabler interface, such as,e.g. a standard or non-standard SOAP/XML interface. In order to do so,however, the network-service address of the respective one or morenetwork-services has to be provided to the third party service provider403. For this reason, a mechanism adapted to forward the network-serviceaddress to the second application 405 of the third party serviceprovider 403, is suggested. With this address, the application 405, willbe able to access one or more required network-services from IMS networkA 401, via the first network 106, although no a-priori businessagreement is set-up between IMS network A 401 and the third partyservice provider 403.

One way of providing access to the network-services of IMS network A 401is based on the establishing of a mobile originated IMS-session betweenthe mobile station 400 and the third party service provider 403,involving the two mentioned IMS networks.

The application 404 may be configured to initiate the proposed addressattachment mechanism in response to some trigger, e.g. upon havingrecognised a demand from application 405 for a network-service,available from IMS network A 401. Typically, however, thenetwork-service address is provided to the application via anIMS-session, which is set-up for another reason than explicitly forretrieving the network-service address, and, thus the proposed addressattachment mechanism is making use of a SIP-session which would havebeen set up anyway.

In a second step 4:2, a SIP message, e.g. a “SIP INVITE” or a “SIPMESSAGE”, is therefore forwarded to a node, typically a session managingnode (not shown), of IMS network A 401, participating in the setting upof the IMS-session. A proposed general architecture including a modifiednode, comprising means for introducing such a an address attachmentmechanism will be described in detail further below, with reference toFIG. 6.

In a next step 4:3, the mobile originated SIP message is inserted intothe received SIP message. According to a first, alternative embodiment,the mobile originated SIP message will always be provided with anetwork-service address, enabling an activated application 405 of thethird party service provider 403 access to network-services of IMSnetwork A 401.

Alternatively, the proposed network-service address attachment procedureis conditional, wherein an arriving SIP message is interrogated, and theparties participating in the IMS-session are verified against one ormore black lists in order to determine if a network-service address isto be attached or not. By introducing one or more black lists, IMSoperator A 401 will be able to deny some parties access to itsnetwork-services. The use of black lists will be described in moredetail further below, with reference to FIG. 6.

In a next step 4:4, the SIP message, and, optionally also a sessionidentifier, which may have been inserted together with thenetwork-service address, is forwarded from IMS-network A 401 to IMSnetwork B 402, optionally, via an intermediate transit network, and inanother step 4:5, the SIP message is forwarded from IMS network B 402 tothe third party service provider 403, where the content of the SIPmessage, including the network-service address, and, optionally, alsothe session identifier, is forwarded to the second application 405.

In a next step 4:6, application 405 determines whether it is in need ofnetwork-services provided from IMS network A 401 for executing arequested service. If required, the network-service address will be usedto access the required network-service, by setting up a connectionbetween the third party service provider 403 and IMS network A 401, viathe first network 406, as illustrated with a final step 4:7. The two-waycommunication between the third party service provider 403 and the IMSnetwork A 401 may be based on, e.g. SOAP/XML web services, or any otherprotocol, suitable for establishing a dynamic business-2-businessrelation. Via the network-service address, application 405, may requestfor a network-service immediately, or after having fetched a list,linking each available network-services to a respective address.

If a session identifier was included in the SIP message of step 4:3,this session identifier may be used by the application 405, e.g. forcharging purposes, when it is included in the signalling, illustratedwith step 4:7, together with the retrieved network-service address.

In response to a request for a network-service, sent in the two-waysignalling of step 4:7, an application server (not shown) from which therequested network-services are accessible, provides the application 405with the relevant data or linking information according to thenetwork-address configuration set in IMS network A 401, and theapplication 405 may use this data or linking information to execute therequested service accordingly.

When establishing such a dynamic business relation, the IMS operator ofIMS network A 401 can authorise what network-services the third partyservice provider 403, as well as other alternative service providers,are allowed to use. The IMS operator of IMS network A 401 may alsospecify conditions for use of the network-services, such as, e.g.whether these network-services are to be free of charge, or to becharged for, according to any predefined charging model. For thispurpose, the session identifier may be correlated with the respectiveIMS session set-up by the IMS operator of IMS network A 401. In thisway, a required policy may be used for all network-services offered fromIMS network A 401. Such a policy could, e.g., specify that somenetwork-services are provided to any IMS session being set-up, wherebythese network-services are charged for on an IMS layer basis, ratherthan on a per network-service.

In another embodiment, which will now be described with reference toFIG. 5, a mobile terminated IMS-session, to be used for the delivery ofa network-service address, is initiated from the third party serviceprovider 403. Also in this embodiment, a user of a first mobile station400, is a subscriber of an IMS operator of a first IMS network, denotedIMS network A 401. The IMS operator of IMS network A 401 has aninterconnection agreement with another operator of a second IMS network,denoted IMS network B 402, which has a business agreement with the thirdparty service provider 403.

In a first step 5:1, an application 404 in the mobile terminal 400,initiates a communication with an application 405 of the third partyservice provider 403, via a first network 406, e.g. in response to auser interaction. In this step, the IMS address, e.g. an IMS public useridentity, of the mobile station, and, optionally, also a sub-address,e.g. an IMS communication services identifier (ICSI) of application 404,is forwarded to application 405. In resemblance to the first embodiment,this communication gives the user access to services provided from thethird party service provider 403. Application 404 may have beendownloaded by application 405, or, if already present in the mobilestation 400, it may have been activated from application 405 or inresponse to a user interaction.

Based on the retrieved information, application 405 may initiate an IMSsession to the terminal address of the mobile station 400, and,optionally, to the sub-address of application 404. Alternatively,application 405 may recognise that a network-service, available at IMSnetwork A 401, is required, whereby an establishment of a mobileterminated session is set-up between the third party service provider403 and the mobile station 400.

In a mobile terminated session set-up according to this secondembodiment, a SIP message is sent from the third party service provider403, to IMS network B 402 in a step 5:2, and the SIP message isforwarded from IMS network B 402 to IMS network A 401 in a next step5:3. Alternatively, the interconnection between IMS network B 402 andIMS network A 401 is executed via a transit network. The SIP message isthen sent from the IMS network A 401 to the mobile station 400 in step5:4, where the content of the SIP message is forwarded to application404 of the mobile station 400. Application 404 responds by initiating aSIP response message, e.g. SIP 200 OK, which is forwarded to IMS networkA 401 in step 5:5.

In a next step 5:6, the network-service address is added to the SIPresponse message in the same way as described in association with thefirst embodiment, described above.

If applicable, a session identifier may also be added to the SIPresponse message at this stage. In a next step 5:7, the SIP responsemessage is forwarded to IMS network B 402, and in a step 5:8, it isforwarded to the third party service provider 403, where the content ofthe SIP response message, is delivered to application 405. Theapplication 405 can now retrieve the network-service address, and, ifinserted together with the network-service address, also the sessionidentifier in a step 5:9. In a next and final step 5:10, application 405will be able to establish contact with IMS network A 401, via the firstnetwork 406, in order to access a network-service.

FIG. 6 is a schematic architecture of IMS network A 401, previouslypresented with reference to FIGS. 4 and 5. A modified node 600, adaptedto attach a network-service address to a SIP message, is connected to aplurality of additional session managing nodes 601, adapted to manageSIP-sessions between IMS network A 401 and external nodes and entities.The node 600, is typically a session managing node which is providedwith the functionality necessary for managing the proposednetwork-service address attachment procedure, in addition to theconventional SIP session managing functionality which the node is set tomanage.

Node 600 comprises a receiving means 602 adapted to receive SIPmessages, which, according to the presented embodiments, arrive from themobile station 400, as described in the two embodiments presented above.

At the receiving means 602, SIP messages are received from a mobilestation 400 in a first step 6:1. The received SIP message, which may bea SIP message of a mobile originated SIP-session, such as, e.g. a SIPINVITE, or a SIP response, responding to a mobile terminatedSIP-session, are forwarded to an inserting means 603 in a step 6:2. Theinserting means 603 may be adapted to insert a network-service addressunconditionally. Alternatively, the inserting means 603 interrogates ablack list database 604 in a step 6:3 to determine whether, e.g. theoriginating and/or terminating party of the IMS-session is/areregistered in a black list. A SIP message comprising a black listedparty will be forwarded unchanged from the receiving means 602, i.e.with no network-service address added. If, however, no blacklistedparticipants can be identified in the SIP message, a network-serviceaddress is added to the SIP message in a step 6:4.

In one embodiment, the respective network-address is attached to a newSIP header of a received SIP message, which may be established, e.g.,according to the following structure:

-   originating-network-services-address=services@operatorA.com wherein    “originating-network-services-address” indicates, e.g. that the SIP    header comprises a network-address of network-services provided from    IMS network A 401.

The network-service address to be attached may be any of a number ofalternative network-service addresses, wherein the respectivenetwork-service address to be inserted is specified according to thepresent configuration of the node 600.

In one embodiment, the network-service address may be the address of acatalogue of network-services, provided by IMS network A 401, whereinthe catalogue can reached, e.g., via a Universal Description, Discoveryand Integration (UDDI) service. A UDDI service is accessed via a URLaddress, addressing a UDDI server. By interrogating such a catalogue, anapplication may be able to find out which services that are available atIMS network A 401, and how to access them, wherein the catalogue isprovided with, e.g. one URL per service.

In an alternative embodiment, the network-service address to be insertedmay instead be configured to be the address of a specificnetwork-service, e.g., a network-service providing location information.In such an implementation, the name of the new SIP header field shouldpreferably indicate this address type, e.g. as:“originating-network-service-address-locationservices”.

In yet another alternative embodiment, the network-address could be anaddress to a specific structure, e.g. an XML document, comprising adescription of network-services, and a listing of all network serviceenabler addresses via which network-services are accessible from IMSnetwork A 401.

As mentioned previously, the inserting means 603 may also be adapted toinsert a session identifier into the SIP message. With a sessionidentifier added, it will be possible to identify the respectiveIMS-session, the originating, and/or the terminating party in theIMS-session, at a later stage of the ongoing communication. Such anidentification may be useful for, e.g. charging purposes, or to hold aparty responsible for abuse when accessing the network.

An alternative to using a session identifier, could be to add the IMSpublic identity of the user in a service request sent by the third partyservice provider 403, in step 4:7 of FIG. 4, or in step 5:8 of FIG. 5,respectively.

Once a mobile station originated SIP message has been handled in theinserting means 603, it is forwarded to any additional functions of node600 in a step 6:5, to be processed accordingly. These functions arerepresented by 606 in the figure. The SIP message is then transmitted toa conventional transmitting means 607 in a step 6:6, from where it isdelivered towards IMS network B 402 in a next step 6.7, and to the thirdparty service provider 403 in a step 6:8.

At the third party service provider 403, the content of the SIP messageis forwarded to the respective application, and if one or morenetwork-services are required by the application, the respective one ormore network-services are accessed via network 406 in step 6:9, usingthe network-service address, retrieved via the SIP message.

IMS network A 401 also comprises a plurality of Application Servers 608,providing one or more network-services via a network service enablerinterface, wherein the one or more network-services are accessed byusing the network-service address.

Both the address database 605, and the black list database 604 are inconnection with the application servers 608 of IMS network A 401, inorder to be continuously updated. Such an updating procedure may beimplemented according to any conventional updating mechanism. Thisprocedure will not be described in any further detail in this document.

An exemplary structure of an address list 700 of the address database700 presented with reference to FIG. 6 is illustrated in FIG. 7. Theaddress list 700 comprises a first network-service address 701, whichmay be, e.g. an address to a service catalogue of operator A, asdescribe previously, and a second address 702, which is, e.g. theaddress of a location service provided by IMS operator A. Although theaddress database 605 may store different network-service addressesassociated with network A, the node 600 is set to only insert onespecified network-service-address, wherein the address is determinedaccording to the configuration of the node.

An exemplary third party application server 800 of a third party serviceprovider 403, adapted to operate in accordance with any of the describedembodiments, will now be described with reference to the simplifiedblock diagram of FIG. 8. A first communication means 801, is adapted toset-up a connection with a mobile station (not shown), via a firstnetwork 406, while a second communication means 802 is adapted to set upan IMS-session with the mobile station via IMS network A 401 (viaanother IMS network 402), as described previously. An application means803 comprises logic, adapted to manage execution of an application 804,which may have been activated, e.g. from a mobile station, via network406, as described previously. The application means 803 comprisesinstructions to set up an IMS-session via IMS network A 401, in order toretrieve a network-service address, as described previously.Alternatively, an associated application, located in the mobile stationactivates an IMS-session between the mobile station served by the thirdparty service provider 403, and the third party service provider 800.

Upon determining that one or more network-services are required, theapplication means 803 sets up a connection with the IMS network A 401,using the network-service address to retrieve the respective one or morenetwork-services from IMS network A 401.

While the invention has been described with reference to specificexemplary embodiments, the description is generally only intended toillustrate the inventive concept and should not be taken as limiting thescope of the invention, which is defined by the appended claims.

1. A method of a third party service provider for retrieving anetwork-service address of at least one network-service offered by anInternet Protocol Multimedia Subsystem (IMS) network of a first IMSoperator, wherein the third party service provider has no businessagreement with the first IMS operator but does have a business agreementwith a second IMS operator providing a second IMS network, the methodcomprising: activating an application of the third party serviceprovider from a mobile station via a first network; establishing anIMS-session between the third party service provider and the mobilestation via the first IMS network, and via the second IMS network;retrieving the network-service address of the at least onenetwork-service at the application of the third party service provider,wherein the network-service address has been inserted into a mobileoriginated SIP message of the IMS-session at a session managing node ofthe first IMS network; determining by the application of the third partyservice provider whether the application requires a network-serviceprovided by the IMS network of the first operator; and accessing arequired network-service from an application server of the IMS networkof the first operator via the first network using the retrievednetwork-service address.
 2. The method of claim 1, wherein the firstnetwork is the Internet.
 3. The method of claim 1, wherein the first IMSoperator has a business agreement with the second IMS operator.
 4. Themethod of claim 1, wherein the two IMS networks are interconnected via atransit network.
 5. The method of claim 1, wherein the network-serviceaddress is inserted into a new network-services address header of theSIP message.
 6. The method of claim 1, wherein the one or morenetwork-services are accessed via a network service enabler interfaceusing the inserted network-service address.
 7. The method of claim 6,wherein the network-service address is an address to any of: a catalogueof network-services or a specific network-service.
 8. The method ofclaim 7, wherein the catalogue also comprises an identifier for eachnetwork-service specifying what protocol to use to access the respectivenetwork-service.
 9. The method of claim 6, wherein the network-serviceaddress is an address to a structure comprising at least one networkservice enabler address.
 10. The method of claim 9, wherein thestructure also comprises an identifier for each network-servicespecifying what protocol to use to access the respectivenetwork-service.
 11. The method of claim 1, wherein a session identifieralso is inserted into the SIP message.
 12. The method of claim 1,wherein the IMS-session is mobile station originated and thenetwork-service address is inserted into a SIP INVITE.
 13. The method ofclaim 1, wherein the IMS-session is mobile station terminated and thenetwork-service address is inserted into a SIP RESPONSE.
 14. A method ofan Internet Protocol Multimedia Subsystem (IMS) network node forproviding a network-service address of at least one network-serviceprovided by a first IMS network of a first operator to a third partyservice provider, wherein the third party service provider has nobusiness agreement with the first operator but does have a businessagreement with a second operator providing a second IMS network, themethod comprising: receiving a mobile station originated SIP message ofan IMS-session established between the third party service provider anda mobile station accessing a network-service of the third party serviceprovider via a first network; interrogating the received SIP message fordetermining whether a terminating and/or originating party of theIMS-session is registered in a black list; if the terminating and/ororiginating party of the IMS-session is registered in a black list,determining that no network-service address is to be inserted into theSIP-message; and if neither the terminating nor the originating party ofthe IMS-session are registered in a black list, performing thefollowing: inserting a network-service address into the SIP message; andforwarding, via the second IMS network, the SIP message to the thirdparty service provider.
 15. A session managing node adapted to provide anetwork-service address of at least one network-service of a firstInternet Protocol Multimedia Subsystem (IMS) network of a first operatorto a third party service provider, wherein the third party serviceprovider has no business agreement with the first operator but does havea business agreement with a second operator providing a second IMSnetwork, the session managing node comprising: a network interface forreceiving a mobile station originated SIP message of an IMS-sessionestablished between the third party service provider and a mobilestation accessing a network-service of the third party service providervia a first network; a processor for inserting a network-service addressinto the SIP message upon having interrogated the SIP message and uponhaving determined that a network-service address is to be inserted intothe SIP message; and a network interface for transmitting the SIPmessage to the third party service provider via the second IMS network;wherein the processor is adapted to determine that no network-serviceaddress is to be inserted into a SIP message if a terminating and/ororiginating party of the IMS-session is found in a black list.
 16. Thesession managing node of claim 15, wherein the network-service addressis provided from an address database, which is continuously updated byat least one application server providing network services.
 17. Thesession managing node of claim 15, wherein the processor is furtheradapted to insert a session identifier into the SIP message.
 18. Thesession managing node of claim 15, wherein the first operator has abusiness agreement with the second operator.
 19. An arrangement for atelecommunication system that comprises a first network, a firstInternet Protocol Multimedia Subsystem (IMS) network of a first operatorserving a mobile station, and a second IMS network of a second operator,wherein the third party service provider has no business relation withthe first IMS network of the first operator, but does have a businessagreement with a second operator providing a second IMS network, thearrangement comprising: one or more nodes at the third party serviceprovider configured for establishing a communication between a firstapplication of the mobile station and a second application of the thirdparty via the first network, and for setting up an IMS session betweenthe mobile station and the third party service provider; and a sessionmanaging node configured for inserting a network-service address of atleast one network-service provided by the first IMS network; whereinsaid one or more nodes at the third party service provider are furtherconfigured for receiving the network-service address and for forwardingit to the second application via the second IMS network; and whereinsaid one or more nodes at the third party service provider are furtherconfigured to: determine whether the second application requires atleast one network-service provided from the IMS network of the firstoperator; set up a connection with an application server of the IMSnetwork of the first operator via the first network if the secondapplication requires at least one network-service from the IMS networkof the first operator using the retrieved network-service address.